MtnBoomer, what is the twist rate on your .243 Win barrel? The reason I ask is I bought a thousand of the 6mm 55 gr Nosler SHOTS bullets for my Stevens (Savage) .243 and the 1 in 9.25” twist keyholes those bullets when I tried to push them close to velocity potential. At very high velocity, the bullets would not stay on an 8 1/2” x 11” target at 100 yards. If I slowed them down (using minimum charges of fast burning powder, Accurate 2015), to around 3200 FPS, they would sort of group at 100 yards, 1.5 - 2.0 MOA. I am saving the last 850 in case my son follows through on his threat to build a 6x45 AR with a 1 in 14” twist barrel. That should be the perfect match for these very thin jacketed bullets. Hopefully you will have better results than I did. Then again, if you aren’t trying for 4,000 FPS, or half inch groups at 100 yards, they might be perfectly acceptable for your purposes.
This same rifle does shoot very small groups with the Nosler 70 gr Varmageddon or Speer 70 gr TNT with close to max charges of Ramshot Big Game at over 3500 FPS.
A 1 in 14" twist 6x45 would be almost useless. My 1 in 8 stabilizes bullets from 58gr (lightest I've tried) to 100gr (heaviest I've tried). It would likely stabilize bullets weighing less and more than what I have listed, but those are what I've tried so far.
